This disclosure relates to biodegradable magnesium alloys, methods of manufacture thereof and articles comprising the same.
Magnesium and its alloys have been investigated for use as materials in biodegradable implants. Although properties of magnesium such as biocompatibility and susceptibility to dissolution are desirable for biodegradable implant applications, its high degradation rate and low strength pose a significant challenge in applications where a longer life cycle (in the body of a living being) is desired.
Elements like aluminum, zinc, calcium, rare earth and other elements have been alloyed with magnesium to improve the mechanical properties of magnesium and to reduce the degradation rate of magnesium and its alloys. In addition to alloying, organic and conversion coatings like micro arc oxidation (MAO) and calcium phosphate coatings have also been employed to develop magnesium-based materials with low degradation rates. These coatings have shown promising results, leading to approximately 70 to 80% initial reduction in degradation rate with calcium phosphate coatings and almost 90% reduction with MAO as compared to uncoated samples. Although these techniques show an improved degradation behavior, they often require specialized equipment, surface pre-treatments and/or simplified substrate geometries. For example, coating a porous metallic foam implant would be difficult using these technologies.
It is therefore desirable find methods and compositions to control the degradation rate of magnesium and its alloys, when these alloys are used in the body of living beings.